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Expansion

Expansion is an expression used in a cooling plant. It relates to the temperature and the process that brings the refrigerant from the condenser side to the evaporator side in the cooling plant.

Expansion is an expression used in a cooling plant. It relates to the temperature and the process that brings the refrigerant from the condenser side to the evaporator side.

All refrigerants have a liquid, evaporation and gas phase like water at 1 bar: liquid below 100 °C, evaporation at 100°C, and gas (steam) above 100 °C.

The boiling temperature for a refrigerant is pressure dependent, where at a curtain pressure relates to a specific boiling temperature. For example R717 ammonia at 2.9 bar boils at -10°C, whereas at 11.7 bar, it boils at 30 °C.

By expanding the refrigerant into an evaporator through an expansion valve, the refrigerant is brought from one pressure to a lower pressure. It starts to boil and evaporate if the "items" near the evaporator are warmer then the evaporation temperature. The expansion is normally controlled by a thermal expansion valve, securing the required evaporation temperature by expanding more or less refrigerant.